The invention concerns an internal combustion engine and a method of operating an internal combustion engine.
Hereinafter the state of the art will be described by means of the example of a stationary gas engine which drives a generator. They generally have between 10 and 24 cylinders (generally a large whole number) which are each ignited by way of a pre-chamber.
In that respect naturally a rotary speed which is as constant as possible is desirable for the internal combustion engine as a change in rotary speed is translated into a frequency deviation in the case of synchronous generators coupled to the internal combustion engines. DIN ISO 8528-5 sets out what quality classes there are in regard to maximum frequency deviations.
Difficulties therefore occur when relatively large changes in load occur. Various measures are then taken to prevent a change in the rotary speed of the internal combustion engine.
That situation occurs for example in so-called island operation.
If for example the power taken from the generator is abruptly greatly reduced (so-called load rejection) it is necessary to prevent the rotary speed of the internal combustion engine from increasing. That can be effected by reducing the amount of energy fed to the internal combustion engine or for example by closing the throttle valve. That leads to a relatively fast reduction in pressure in the distributor chamber (intake manifold) of the internal combustion engine.
In the case of severe load rejections that rapid reduction in pressure in the intake manifold cannot be sufficiently quickly followed by pressure regulation for the pre-chamber gas feed.
Inaccurate pre-chamber gas metering can lead to unstable combustion processes and thus defective ignition characteristics and deflagration phenomena. The unfavorable pressure differences which occur in that case in a pre-chamber gas feed system as between the pre-chamber system and the intake manifold cylinder of the internal combustion engine can cause defective ignition processes and deflagration phenomena. That makes it difficult to comply with regulatory safety standards.